Need to build an sidebar extension that fetches LinkedIn search results using JS wihtout using API

I am learning JavaScript . I need to build a sidebar chrome extension that fetches LinkedIn profile result’s data into the extension.

Like if someone logs into LinkedIn and searches for developer, next he clicks my extension and he gets the name and email of that person in that extension. The names should be in the same order as the search results. I don’t know where to start for this.

I have googled but it says using APIs but I don’t think I would need APIs for this. Just some good dom manipulating would do the thing I guess. But maybe I am wrong.

I have built extensions before but this is something I am not getting.